Forbes’ writer Natalie Robehmed explained how the rankings—which are based on the period from June 2015 to June 2016—were arrived at: “estimates are compiled by looking at print, ebook, and audiobook sales from Nielsen BookScan figures, considering TV and movie earnings and talking to authors, agents, publishers and other experts.” Earnings are pre-tax and other fees are not deducted.

The full list of top-earning authors across all categories will be published later this month, the publication said.

Michele Molnar is associate editor of EdWeek Market Brief. She is also a reporter who covers industry and innovation for Education Week. Michele began working as a contributing writer for Education Week in 2012, covering parents' influence on education. She joined the staff in 2013 to write about the intersection of education and business in the pre-K-12 marketplace.